The cdma2000 High Rate Packet Data Air Interface Specification published as TIA/EIA/IS-856, and more specifically the QUALCOMM CDMA2000 1xEV-DO version, is an air interface optimized for the delivery of high-speed wireless data to mobile and fixed terminals.
In 1xEV-DO, an access terminal (AT) is a device with a radio modem and a data interface that allows the user to access a packet data network through the 1xEV-DO access network. An AT is analogous to a Mobile Station in IS-41 cellular network.
An Access Network (AN) is network equipment providing data connectivity between a packet-switched data network, for example, the Internet, and the ATs. As referred to herein, the AN can comprise a modem pool transceiver alone, and, additionally, other network equipment, for example, a modem pool controller.
The forward link (FL) refers to communications from the AN to the AT. Correspondingly, the reverse link (RL) refers to communications from the AT to the AN.
Multiple ATs can be communicating within a sector covered by a single BTS. The AN is limited by a received threshold power. The received power is a function of the number of ATs in the sector and the data rate of each AT in the sector. An AT transmitting at high data rate transmits signals at a higher power than an AT transmitting at a low data rate. When an AN approaches its received threshold power, the AN can send a message on the reverse link activity channel to all ATs in the AN's sector to reduce transmit rate. The transmitted signals of an AT can cause channel interference for a particular AT. Multiple ATs transmitting signals can cause even greater channel interference for the particular AT.
A need therefore exists for a method and apparatus for reducing the channel interference in a sector serving multiple ATs.